A number of readers sent me links this week about the new Sony patent for ultrasonic neural stimulation. It is definitely interesting and could represent a useful new approach to non-invasive brainstate manipulation. However, it is by no means anywhere near being useful for entertainment, virtual reality, or mind control. Our understanding of how the brain works is still far too primitive. Even if the Sony technology was actually working (which it is not, by the way -- it is just an idea, no working prototype was built or tested), it would be a long time before we would know where to aim it. By the time neuroscience has reached a point where thoughts can be stimulated reliably by an external source, this Sony patent and its continuations will have long-since expired. I am guessing we are at least 100 years away from having enough of an understanding of the brain for such a technology to be applicable to mass markets. Meanwhile it might be a useful tool for research -- it's certainly more precise than magnetic stimulation, and it is a lot less damaging than creating physical lesions. It will be interesting to see where this goes, if anywhere. But even if it does go somewhere, there is a chance that mere neural stimulation may not be enough to generate fully-immersive states of consciousness. While such stimulation may trigger particular memories or maybe even perceptual experiences, the complexity required to generate a complete experience -- encompassing all sensory modalities and with enough internal detail and logical consistency to be believable -- is far beyond what we can presently even imagine. In the end, I think it would be more fruitful to leverage the brain's ability to generate dreams than to attempt to build conscious experiences from scratch. We should really do more research into the mechanism of dreaming, and in particular, into the mechanisms of lucid dreaming. By combining hypnosis with lucid dreaming we can create completely immersive states of consciousness today, without any special technology or neural stimulation. And these "simulations" are already far richer and more interactive than anything Sony will come up with in the next several hundred years.